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June 21, 1955 B. R. STRICKLAND DEASPHALTING OPERATION Original FiledFeb. 27, 1952 Exam GASOLIUE Aux: GAS

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505m" 3 GATAu/s'r boT TOM'S Qbczrrzes Q. Gina Hand {Sm/enterabbornagUnited States Patent Ofiice Re. 24,025 Reissued June 21, 1955DEASPHALTING OPERATIGV Barney R. Strickland, Westfield, N. 5., assignorto Essa Research and Engineering Company, a corporation of DelawareOriginal No. 2,696,458, dated December 7, 1954-, Serial No. 273,712,February 27, 1952. Application for reissue March 22, 1955, Serial No.4%,il9t

3 Claims. (Cl. 196--14.ll)

Matter enclosed in heavy brackets E appears in the original patent butforms no part of this reissue specifica tion; matter printed in itaiicsindicates the additions made by reissue.

The present invention is broadly concerned with an improved process forthe removal of asphaltic constituents from residual oils wherebyincreased yields of higher quality deasphaitcd oils are obtained. Thepresent invention is more particularly concerned with an improvedprocess for the preparation of satisfactory feed stocks for crackingoperations, whereby higher quality hydrocarbon products boiling in thegasoiine and heatbig oil boiiing ranges are obtained by an efficientoperation. In accordance with the present invention, a residual oil ismildly thermally cracked or visbroken under controlled conditions. Lowboiling hydrocarbon constituents, as for example hydrocarbons boiling inthe motor fuel and heating oil boiling ranges are removed from thevisbrolten residuum. The residuum is then deasphalted. The resultingdeasphalted product is utilized as a high quality fuel or employed inthe catalytic cracking operation.

It is Well known in the art to treat mineral oils by various processesin order to remove undesirable high boiling and asphaltic constituentsfrom these oils. For example, it is known to employ light hydrocarbonsolvents, as for example, hydrocarbons such as propane and butane, inorder to remove undesirable constituents, such as asphalticconstituents, therefrom. In these operations various temperatures andpressures are employed, as well as various solvent to oil ratios. It isalso known in the art to use various other processes for the removal ofcarbon-forming and ash-forming constituents therefrom in order toprepare high quality lube and fuel oils. Other processes have alsogenerally been directed toward the preparation of satisfactory highboiling feed stocks for a cracking operation, particularly for afluidized solids catalytic cracking operation.

It has now been discovered that undesirable high boiling constituentsmay be efiiciently removed from feed stocks boiling in the reduced crudeboiling range, providing the reduced crude or residual oil is mildlyvisbroken and then treated with a deasphalting solvent, as for example,propane or butane. The process of the present invention may be readilyunderstood by reference to the drawing illustrating one embodiment ofthe same.

Referring specifically to the drawing, a feed oil, as for example a WestTexas crude, is introduced into distillation zone 1 by means of feedline 2. Temperature and pressure conditions in zone 1 are adjusted tosecure the desired fractionation of the crude oil. Low boilinghydrocarbon gases are removed overhead from zone 1 by means of line 3; ahydrocarbon fraction boiling in the light naphtha range is removed bymeans of line 4; a hydrocarbon fraction boiling in the heavy naphtharange is removed by means of line 5, while a gas oil fraction is removedby means of line 6. A fraction boiling in the reduced crude boilingrange, as for example in the range above about 600 to 700 F., preferablyboiling in the range above about l000 R, is segregated as a bottomsfraction by means of line 7. It is to be understood that zone 1 maycomprise any suitable number and arrangement of distillation zones orstages.

in accordance with the present invention, the high boiling reduced crudeis passed into visbreaking zone 10 wherein the oil is subjected totemperature, pressure and time conditions to mildly reduce the viscosityas hereinaitcr described. the visbrolten product is withdrawn fromvisbrealting zone in by means of line 70 and passed into distillationzone ii. Temperature and pressure conditions in zone 71 are adapted tosegregate hydrocarbon constituents boiling below about 650 1*. from theresiduum. Hydr roon constituents boiling in the motor fuel boiling rangeand below are removed from zone 71 by means of line 72 While hydrocarbonconstituents boiling in the heating oil boiling range are removed fromzone it by means of iine 73. The visbroiten residuum boiling above abouti) 5., preferably boiling above about 1000 F. is withdrawn from thebottom of distillation zone 71 by means of iinc 74 and introduced into ad6' i3ll.lllil1g zone r3 .vhcrein it is preferably countercurrcntlycontacted Vri dcasphalting solvent, as for example, propane or to orequivalent solvent which is introduced into deusphuhing zone 8 by meansof line 9. Temperature and pressure conditions in zone 8 are adjusted tosecure the desired removal or asphaltic constituents from the residualoil. A residual oil-propane mixture is removed overhead from zone 8 bymeans of line t3 and introduced into a distillation zone 15. Temperatureand pressure conditions in zone 15 are adjusted to remove overhead bymeans of line 5! propane or other solvent which is preferably recycledto Zone 8.

A dcasphalted residual fraction is removed from the bottom ofdistillation zone 15 by means of line 51 and may be combined with aportion of the gas oil stream withdrawn from zone 1 which is introducedinto line 51 by means or. line 52. This virgin gas oil may be removedfrom the system if desired by mcans of line 60. The deasphaltcd oil maybe withdrawn from the system by means of line 61 and utilized as a highquality fuel.

The asphaitic constituents are removed from zone 8 by means oi line $5and passed to a distillation zone 54, wherein a separation is madebetween the propane and the asphaltic constituents. The propane or othersolvent is removed overhead by means of line 55 and preferably recycledto zone 8 while the asphaltic constitucnts are removed a bottoms bymeans of line 56 and further refined or handled as desired. It is to beunderstood that zones 8, i5, 10, 'fl and 54 may comprise any suitablenumber and arrangement of stages.

The present invention is broadly concerned with an improved process forthe removal of undesirable high boiling constituents and asphalticconstituents from residual oils. The invention comprises utilizing inconjunction with conventional solvents, a mild visbreaking operation.The resultant deasphalled product of higher yield, as pointed outheretofore, is suitable for the production of high quality fuel oils, ad is particularly adapted as a feed stock to a fluid catalytic crackingoperation.

The deasphalting solvent may comprise low boiling hydrocarbons, as forexample, those containing from 2 to 5 carbon atoms in the molecule, ormixtures thereof. Particularly desirable solvents comprise propane andbutane. The amount of solvent used per volume of oil may vary from T. toit), preferably in the range from 4 to 6 volumes of solvent per volumeof oil. When using propane as a solvent, the mixture is generally heatedto a temperature in the range from about 110 F. to 180 F., preferably toa temperature in the range from 120 to 160 F. When usi butane a solvent,the temperature may be in the range of 150 to 350 F.. preferably in therange of 200 to 300 P. if a mix ture of propane and butane is used,intermediate temperatures to those used with the two materialsseparately are employed.

The deasphalting operation may comprise a batch operation or acountercurren treating operation wherein the oil is introduced into thetop of the tower, the propane or other solvent is introduced into thebottom of the tower, and wherein deasphalted oil is removed from the topof the tower and asphaltie constituents from the bottom of the tower. inconducting an operation of this character, a temperature gradient ispreferably maintained throughout the tower.

As heretofore disclosed, the deasphultcd residual fraction withdrawnfrom zone may be with d. as a fuel or in accordance with a specificadaptatir the pres-- ent invention, may be used as such or corruincdwith a portion of the gas oil fraction segregated in zone A andintroduced into a fluid catalytic cracking operation.

The fluid catalytic cracking operation comprises three sections:cracking, regeneration, and fractionation. The cracking reaction takesplace continuously in one reactor. the spent catalyst being removedcontinuously for regeneration in a separate vessel, from which it isreturned to the cracking vessel. Continuity of flow of catalyst as wellas of oil is thus accomplished, and the characteristic features offixed-bed designs involving the intermittent shifting of reactorsthrough cracking. purging, and regeneration cycles are eliminated.

Regeneratcd catalyst is withdrawn from the rcgenerator I and flows bygravity down a standpipe, wherein a sulliciently high pressure head isbuilt up on the catalyst to allow its injection into the fresh liquidoil stream. The resulting mixture of oil and catalyst flows into the reaction vessel, in which gas velocity is intentionally low, so that ahigh concentration of catalyst will result. The cracking that takesplace results in carbon deposition on the catalyst, requiringregeneration of the catalyst. The cracked product oil vapors arewithdrawn from the top of the reactor after passing through cycloneseparators to free them of any entrained catalyst particles, while thespent catalyst is withdrawn from the bottom of the reactor and isinjected into a stream of undiluted air which carries the catalyst intothe regeneration vessel. The products of combustion resulting from theregeneration of the catalyst leave the top of this vessel and passthrough a series of cyclones where the bulk of the entrained catalyst isrecovered. The regenerated catalyst is withdrawn from the bottom of thevessel to complete its cycle.

Again referring specifically to the drawing, in accordance with aspecific preferred adaptation of the present invention, the treated oilremoved by means of line 51 is introduced into a catalytic cracking zone22.

Temperature and pressure conditions in cracking zone 22 are adjusted tosecure the desired conversion of the feed oil. Cracked products areremoved overhead from zone 22 by means of line 23 and passed into afractionation zone 24. Temperature and pressure conditions infractionation zone 24 are adjusted to remove overhead by means of line25 hydrocarbon constituents boiling in the gasoline and lower boilingranges. This stream is passed to a stabilizing unit where a gasolinefraction of the desired volatility is segregated. A heating oil fractionis removed by means of line 26 while a fraction boiling in the lightcycle oil boiling range is removed by means of line 27. A bottomsfraction or heavy cycle oil is removed by means of line 23 and handledas desired. Spent catalyst is removed from the bottom of zone 22 bymeans of line 29 and passed into a regeneration zone 30 by means of line31. Suflicient air is introduced into the system by means of line 32.Regenerated catalyst is removed from the bottom of zone 30 by means ofline 33 and passed to the reactor along with the feed by means of line51.

The invention is broadly concerned with the removal of undesirablematerials from petroleum oils, particularly from petroleum oils boilingin the reduced crude boiling range. Petroleum oils treated in accordancewith the present invention are particularly adapted as feed stocks for acatalytic cracking reaction. Although the invention may be adapted forthe treatment of mineral oils boiling over wide ranges as pointed outabove, it is particularly adapted for the treatment of oils boilingabove about 860 F., preferably boiling above about 1000 F.

As discussed above, the invention is particularly concerned with animproved operation which comprises the treatment of a reduced crude byvisbreaking followed by deasphalting the same. The deasphalted residuumcomprises an excellent feed stream for a catalytic cracking unit. It iswell known in the art to produce cracked naphthas by a fluidized solidscatalytic operation wherein the cracked product comprises constituentsboiling in the motor fuel boiling range, as for example, below about 430F. The cracked product also comprises normally gaseous constituents, asfor example, those containing three carbon atoms and less in themolecule. The fluidized solids technique for processing feed fractions,as for example, gas oils, heavy residuums and other feed stocks for theproduction of hydrocarbon fractions boiling in the motor fuel boilingrange is a conventional one such as described in conjunction with thedrawing.

As pointed out heretofore, the system of a fluidized solids techniquecomprises a reaction zone and a regeneration zone, employed inconjunction with a fractionation zone. The reactor and the catalystregenerator are arranged at approximately an even level. The operationof the reaction zone and the regeneration zone is conventional, whichpreferably is as follows:

An overflow pan is provided in the regeneration zone at the desiredcatalyst level. The catalyst overflows into a withdrawal line whichpreferably has the form of a U-shaped seal leg connecting theregeneration zone with the reaction zone. The feed stream introduced isusually preheated to a temperature in the range from about 500 to 650 F.in exchangers in heat exchange with regenerator flue gases which areremoved overhead from the regeneration zone, or with cracked products.The heated feed stream is withdrawn from the exchangers and introducedinto the reactor. The seal leg is usually willciently below the point offeed oil injection to prevent oil vapors from backing into theregenerator in case of normal surges. Since there is no restriction inthe overflow line from the regenerator, satisfactory catalyst flow willoccur as long as the catalyst level in the reactor is slightly below thecatalyst level in the regenerator when vessels are carried at about thesame pressure. Spent catalyst from the reactor flows through a secondU-shaped seal leg from the bottom of the reactor into the bottom of thercgenerator. The rate of catalyst flow is controlled by injecting someof the air into catalyst transfor line to the regenerator.

The pressure in the regenerator may be controlled at the desired levelby a throttle valve in the overhead line from the regenerator. Thus, thepressure in the regenerator may be controlled at any desired level by athrottle valve which may be operated, if desired, by a differentialpressure controller. If the pressure differential between the twovessels is maintained at a minimum, the seal legs will prevent gasesfrom passing from one vessel into the other in the event that thecatalyst flow in the legs should cease.

The reactor and the regenerator may be designed for high velocityoperation involving linear superficial gas velocities of from about 2.5to 4 feet per second. However, the superficial velocity of the npflowinggases may vary from about l-5 and higher. Catalyst losses are minimizedand substantially prevented in the reactor by the use of multiple stagesof cyclone separators. The regeneration zone is provided with cycloneseparators. These cyclone separators are usually from 2 to 3 and morestages.

Distributing grids may be employed in the reaction and regenerationzones. Operating temperatures and pressures may vary appreciablydepending upon the feed stocks being processed and upon the productsdesired. Operating temperatures are, for example, in the range fromabout 800 to 1000 F., preferably about 850-950 F., in the reaction zone.Elevated pressures may be employed, but in general pressures below 100lbs. per sq. in. gauge are utilized. Pressures generally in the rangefrom 1 to 30 lbs. per sq. in. gauge are preferred. A catalyst holdupcorresponding to a space velocity of 0.5 to weights per hour of feed perweight of catalyst is utilized. A preferred ratio is 1 to 3. Catalyst tooil ratios of about 3 to 10, preferably about 6 to 8 by weight are used.

The catalytic materials used in the fluidized catalyst crackingoperation, in accordance with the present invention, are conventionalcracking catalysts. These catalysts are oxides of metals of groups II,III, IV and V of the periodic table. A preferred catalyst comprisessilicaalumina wherein the weight per cent of the alumina is in the rangefrom about 5 to 20%. Another preferred catalyst comprisessilica-magnesia where the weight per cent of the magnesia is about 5% to20%. These catalysts may also contain a third constituent, as forexample, ThO2, W03, BeO, Bi203, CdO, U03, B203, SnOz, MnO, CrzOs, CaO,T1203, and CezOs present in the concentration from 0.05% to 0.5%. Thesize of the catalyst particles is usually below about 200 microns.Usually at least 50% of the catalyst has a micron size in the range fromabout 20-80. Under these conditions with the superficial velocities asgiven, a fluidized bed is maintained wherein the lower section of thereactor, a dense catalyst phase exists While in the upper area of thereactor a dispersed phase exists.

The above described operation, as pointed out, has not been entirelysatisfactory for cracking heavy oils such as a reduced crude due toexcessive formation of carbon and ash on the catalyst. However, bymildly visbreaking reduced crude and deasphalting the same, unexpecteddesirable results are secured.

While the exact mechanism is not entirely understood, it is felt thatthe mild visbreaking operation employed as described in the presentinvention causes certain ash constituents in the residuums to decompose.These organic metallic ash compounds are converted to a form which canreadily be removed on deasphalting. It is also felt that these residuacontain constituents such as resins which function as peptizing agentswhich tend to hold the oil and asphaltic constituents in a single phase.The mild visbreaking operation of the present invention causes theseresins to decompose, resulting in a greater yield of deasphalted oil.

On the other hand, a normal or severe visbreaking operation decreasesthe yields of deasphalted oil as well as impairs its quality, comparedto mild visbreaking.

The mild visbreaking operation is secured by controlling variousinterrelated operating conditions such as feed rates, pressure, recyclerates, temperature and time. In general it is preferred that relativeiylow temperatures and contact times be used as compared to normalvisbreaking operations. In visbreaking operations it has been known thatthe insoluble material in 86 naphtha readily approaches the originalConradson carbon of the feed and then levels off. One method is tocontrol operating conditions so that a minimum conversion is attainedand that the naphtha-insoluble content of the visbroken product (portionboiling above about 650 F.) approaches the Condradson carbon content ofthe original residuum feed. The viscosity of the product as compared tothe feed should be Within preferably Within 25%.

The present invention may be more fully understood by the followingexamples illustrating the same:

EXAMPLE 1 A residual oil was visbroken in one operation to yield 5 byvolume of hydrocarbons boiling within the range of butane to about 430F. vapor temperature. In a second operation, the yield was 9%. Bothvisbroken products were distilled to remove gasoline and heating oilproduced and the higher boiling bottoms fraction was then deasphalted.The results of these operations are shown in the following table. Theresidua boiled above about 650 F.

DEASPHAL'IING OF VIRGIR RESIDUUM AND VISBROKEN RESIDUUMS [One-stage,using mixed butanes: 65% n-butane and 35% isobutane] Vlsbreakor ResiduumVlsbreaker Residuum Material Deasphalted Virgin Reslduum from 6% Oonv.(Ct/430 from 9% Conv. (Ci/430 F. Yield) F. Yield) DeasphsltingConditions:

Temperature 200 F 200 F. Solvent Treat". 07 600%. Mixing Time. 30Minutes. Settling Time do Do.

Yields Wt. Percent:

Oil

53 (55 Vol. Percent).... 47

67 (71 Vol. Percent). 33.

Feed

Asphalt Oil Feed Asphalt Inspections:

Specific Gravity API Gravity. Viscosity-- VISBREAKING CONDITIONS[Ones-through coil only.]

(ll/430 F. V. T. Yield, Vol. Percent 5 9 From the above, it is readilyapparent that the viscosity of the visbroken residuum from visbreakingto 5% gasoline yield was not substantially lower than the viscosity ofthe original residuum (952 vs. 990). On the other hand, the viscosity ofthe residuum from visbreaking at 9% conversion was appreciably lowerthan the viscosity of the original residuum (395 vs. 990).

It is to be noted that in both operations the yield of the deasphaltedoil was increased appreciably (55 volume percent to 71-72 volume percentbased on feed to deasphalting).

The yields of deasphalted oil based upon the virgin residuum in the twooperations were as follows:

Vlsbreaking to Residuum Pretreatment None 5% Con- 9% Con version version011 Virgin Reslduum:

Weight Percnt.. 53 B 61 Volume Percent" 55 68 04 It is readily apparentthat the yield of deasphalted oil is appreciably greater at a 5%conversion as compared to a 9% conversion visbreaking operation.

EXAMPLE 2 Various tests were made to determine the potential carbonwhich the deasphalted oils would deposit on the catalyst in a fluidcatalytic cracking operation under the same operating conditions. Theresults of these tests are It is apparent from the above thatapproximately 100% more carbon is formed on the catalyst whenvisbreaking to a 9% conversion as compared to visbreaking mildly to a 5%conversion.

As pointed out heretofore, the mild visbreaking will be a function ofpressure, contact time and temperature. The operations should be socontrolled that a minimum conversion is attained wherein the naphthainsoluble content of a visbroken product approaches the Conradson carboncontent on the original residuum feed. Effective contact time may beexpressed as a reciprocal relationship, v./hr./v., which is volume offeed oil per hour per volume of reaction zone above 750 F. If thetemperature be relatively low, then the contact time is long or thev./hr./v. is relatively low, whereas if higher temperatures areemployed, the v./hr./v. is higher. The following table illustratesapproximate temperaturev./hr./v. relationships 5 Temperature, F.:V./l1r./v. 750 1 800 3 860 900 50 in 920 75 What is claimed is:

[1. A process for the removal of asphaltic constituents from residualoils which comprises heating the residual oil at a temperature of about750 F. to 920 F. at a feed rate of about 1-75 volumes of oil per hourper volume of the heating zone to provide a treated productcharacterized by conversion of no more than about 5% of hydrocarbonsboiling in the range below 430 F., removing the said hydrocarbonsboiling below about 430 F. by fractionation, and thereafter treating theresidual oil with a deasphalting solvent under conditions to separateasphaltic constituents from the treated product providing a treatedresidual oil characterized by a viscosity not substantially lower thanthe original residual oil, and a content of insoluble material in 85 A.P. I. gravity naphtha approaching the Conradson carbon content of theoriginal residual oil] [2. The process defined by claim 1 in which thesaid residual oil to be treated boils above about 650 F] [3. The processdefined by claim 1 in which the said deasphalting solvent comprises alow boiling hydrocarbon solvent] 4. A process for the removal ofasphaltic constituents from residual oils which comprises heating theresidual oil at a temperature of about 750 F. to 920 F. at a feed rateof about 1-75 volumes of oil per hour per volume of the heating zone toprovide a treated product characterized by conversion to no more thanabout 5% of hydrocarbons boiling in the range below 430 F., removing thesaid hydrocarbons boiling below about 430 F. by fractionation, andthereafter treating the residual oil, characterized by a viscosity notsubstantially lower than the original residual oil and a content ofinsoluble material in 86 A. P. I. gravity naphtha approaching theConradson carbon content of the original residual oil, with adeasphalting solvent under conditions to separate asphaltic constituentsfrom the treated product.

5. The process defined by claim 4 in which the said residual oil to betreated boils above about 650 F.

6. The process defined by claim 4 in which the said deasphalting solventcomprises a low boiling hydrocarbon solvent.

References Cited in the file of this patent OTHER REFERENCES Industrialand Engineering Chemistry, vol. 42, No. 10, October 1950, pages2088-2095 incl. (Article by Oden et a1.)

